An express wagon bogie is an important part of an express railway freight transport vehicle, and the structural performances of the express wagon bogie play an important role in the running smoothness, stability and safety of the vehicle. By means of the express wagon bogie, the vehicle can transmit various loads and action forces from a vehicle body to wheels as well as from tracks to the vehicle body and ensure that the axle load is distributed uniformly. At present, the express wagon bogies at home and abroad generally adopt two-stage of suspension structures, that is, a primary axle box positioning suspension device and a secondary central suspension device; the general two-stage suspension structures are adopted to guarantee the high-speed running of the vehicle, wherein the secondary central suspension device is a suspension device arranged between a frame and a bolster of the bogie and is used for reducing impact, attenuating vibration and improving the running stability of the vehicle.
FIG. 1 is a top view of the structure of a wagon bogie in the prior art, and FIG. 2 is a front view of the structure of the wagon bogie in FIG. 1. As shown in FIG. 1 and FIG. 2, a central suspension device in the railway wagon bogie mainly comprises a frame 3, a bolster 2, a longitudinal traction connecting rod device 4 and a rubber-metal pad spring 1. During the running of the vehicle, the transmission sequence of the longitudinal traction force and the braking force of the vehicle is that: the longitudinal force and the braking force from a bogie center plate 9 are transmitted to the bolster 2, then to the longitudinal traction connecting rod device 4 via the second traction connecting rod base 41 on the bolster 2, then to the first traction connecting rod base 42 on the frame 3 via the longitudinal traction connecting rod device 4, then to the frame 3 via the first traction connecting rod base 42, then to an axle box spring group 8 of an axle box suspension device via the frame 3, and finally to a wheel set via the axle box spring group 8. The transmission sequence of the transverse force of the vehicle is that: the transverse force from the bogie center plate 9 is transmitted to the bolster 2, then to the longitudinal traction connecting rod device 4 via the bolster 2, then to the frame 3 via the longitudinal traction connecting rod device 4 and the rubber-metal pad spring 1, then to the axle box spring group 8 via the frame 3, and finally to the wheel set via the axle box spring group 8; and the transmission sequence of the transverse force on the wheel set of tracks is that: the transverse force is transmitted to the frame 3 via the wheel set, then to the longitudinal traction connecting rod device 4 and the rubber-metal pad spring 1 via the frame 3, and finally to the bolster 2 after being buffered by the longitudinal traction connecting rod device 4 and the rubber-metal pad spring 1.
FIG. 3 is a schematic structural diagram of the central suspension device in FIG. 1, and FIG. 4 is a schematic structural diagram of rubber-metal pad spring in FIG. 3. As shown in FIG. 3 and FIG. 4, the frame 3 and the bolster 2 are connected together via the rubber-metal pad spring 1 in the vertical direction, and the frame 3 and the bolster 2 are connected together via the longitudinal traction connecting rod device 4 in the longitudinal direction. Each rubber-metal pad spring 1 comprises a rubber body 15, an upper liner 16, an upper positioning pin 17, a lower liner 18 and a lower positioning pin 19. The upper liner 16 and the upper positioning pin 17 are welded together, and the upper positioning pin 17 is inserted into an opening of a lower cover plate of the bolster 2, so that the rubber-metal pad spring 1 and the bolster 2 are connected in a positioning way; the lower liner 18 and the lower positioning pin 19 are welded together, and the lower positioning pin 19 is inserted into an opening of an upper cover plate of the frame 3, so that the rubber-metal pad spring 1 and the frame 3 are connected in a positioning way. When the vehicle provided with the central suspension device with such structure is running, the rubber-metal pad spring is subjected to compression deformation under the action of vertical load and is subjected to shearing deformation under the action of transverse load, therefore, the vertical vibration and the transverse impact can be buffered so as to reduce the dynamic stress. However, for the rubber-metal pad spring in the central suspension device, the rubber-metal pad spring with a larger rigidity structure is needed in the transverse direction in order to guarantee the vertical carrying capacity, but the running stability of an empty vehicle is affected by the increased transverse rigidity; meanwhile, the vertical deflection decreases with the increase of the transverse rigidity, so that the adaptability of the vehicle to the tracks is reduced during the high-speed running, thereby resulting in the problem that the vehicle derails easily.
FIG. 5 is a schematic structural diagram of the longitudinal traction connecting rod device in FIG. 1. As shown in FIG. 5, the longitudinal force and the braking force are transmitted to a rubber pad assembly 47 via the second traction connecting rod base 41 on the bolster 2, then to a traction connecting rod 43 via a nut 44, then to a rubber pad assembly at the other end of the traction connecting rod 43 via the traction connecting rod 43, and then to the first traction connecting rod base 42 on the frame 3, and finally to the frame 3, wherein an inner cylinder 46 is a non-metal wear-resistant piece, and a gasket 45 is used for preventing the nut 44 from loosening. When the longitudinal traction connecting rod device with the structure is under the transverse acting force transmitted via the bolster 2 from the bogie center plate 9, the rubber pad assembly 47 is deformed after being twisted and compressed, the compression rigidity is larger, and the transverse additional rigidity of the bogie is increased by about 30%, so that the dynamics performance of the vehicle is seriously affected, thereby not being beneficial for the running of the empty vehicle.